1. Field of the Invention
The present invention relates generally to vinyl ester urethane resins, to methods of preparing said resins, and to compositions containing said resins. More particularly, the invention relates to vinyl ester urethane resins having the following general formula: EQU B--I--A--M].sub.y A--(I--B).sub.q
wherein
A is a radical derived from a polyoxyalkylene bisphenol, A having the following formula: ##STR1## wherein R' is C.sub.1 -C.sub.4 alkylene group,
X is halogen or a C.sub.1 -C.sub.4 alkyl group, PA1 a is an integer equal to from 0 to 2, and PA1 m and n are integers each of which is equal to at least 1 and the sum of which is equal to from 2.0 to about 8.0; PA1 X is halogen or a C.sub.1 -C.sub.4 alkyl group, PA1 a is an integer equal to from 0 to 2, and PA1 m and n are integers each of which is equal to at least 1 and the sum of which is equal to from 2.0 to about 8.0; PA1 X is halogen PA1 a is an integer equal to from 0 to 2, and PA1 m and n are integers each of which is equal to at least 1 and the sum of which is equal to from about 2 to about 8. PA1 R' is an alkylene group containing 2 to 5 carbon atoms, and PA1 n is an integer equal to from 1 to about 3.
M is a radical derived from (A) an unsaturated, aliphatic, polycarboxylic acid or an anhydride thereof, (B) a saturated aliphatic polycarboxylic acid or an anhydride thereof, (C) an aromatic polycarboxylic acid or anhydride thereof or (D) mixtures of A, B, or C;
I is a radical derived from an isocyanate having an isocyanate functionality greater than 2;
B is a radical derived from a monohydroxyl-terminated ester of unsubstituted or substituted acrylic or methacrylic acid wherein the substituents are halogen or C.sub.1 -C.sub.4 alkyl groups;
Y is an integer equal to from 1 to about 12.
The resins are prepared by reacting an isocyanate having a functionality of greater than two, and a monohydroxyl-terminated ester of the substituted or unsubstituted acrylic acid with the condensation product prepared by reacting a polyoxyalkylene bisphenol A with a polycarboxylic acid or anhydride. The resins are useful in thermosetting fiber reinforced laminates or castings having improved retention of properties at elevated temperatures.
2. Description of the Prior Art
Vinyl ester urethanes are known in the art. See for example Ford, E. C. Jr., et al., U.S. Pat. No. 3,876,726 which discloses vinyl ester urethanes prepared by reacting a polyoxyalkylene bisphenol A with a unsaturated aliphatic dicarboxylic acid and reacting the product thereof with a diisocyanate and a hydroxyl-terminated ester of a methacrylic or an acrylic acid. It has now been discovered that certain vinyl ester urethanes which utilize isocyanates having higher isocyanate functionalities have increased retention of properties in the cured products when subjected to a high temperature environment. Additionally, the resins have shown a remarkable improvement in process properties of sheet molding formulations particularly in the areas of handleability, such a tackiness and green strength and maturation of the uncured resins resulting in more efficient processes.